1. Field of the Invention
The present invention relates to a disk-loading apparatus for loading a CD and a DVD to their reproducing positions, and more particularly to a disk-loading apparatus in which a single motor is used to move a disk-carrying tray and to rotate a drive chassis that carries a recording-and-reproducing unit having a pick-up.
2. Description of the Related Art
FIG. 10 is a top view of a conventional disk-loading apparatus when a tray is at a disk-discharging position.
Referring to FIG. 10, a main chassis 2 supports a tray 3 thereon such that when the tray 3 is driven to move between a disk-loading position (FIG. 13) and a disk-discharging position (FIG. 10), guides 2a-2f guide the tray 3 to slide on the main chassis 2. The tray 3 has a disk-carrying surface 3d on which a disk, not shown, is placed. The tray 3 moves into the disk-loading apparatus for loading the disk and out of the disk-loading apparatus for discharging the disk. The tray 3 has a rack 3a formed in an underside on one side of the tray 3. The tray 3 also has generally L-shaped guide grooves 3b and 3c formed in the underside thereof, the guide grooves 3b and 3c guiding bosses 50a and 50b of a cam slider 50, respectively. The main chassis 2 is mounted to a disk-player chassis, not shown, by means of rubber dampers 80, 81, and 82.
FIG. 11 is a perspective view of a pertinent portion of a rotation-transmitting mechanism of a loading motor 122 of FIG. 10.
Referring to FIGS. 10 and 11, the drive gear 120 includes a small gear (pinion) 120a and a large gear 120b. The drive gear 120 is mounted to the main chassis 2 so that the drive gear 120 is rotatable about an axis parallel to a Z-axis and the small gear 120a is in mesh with the rack 3a formed in the tray 3. Likewise, an intermediate drive gear 121 is mounted to the main chassis 2 so that the intermediate gear 121 is rotatable about an axis parallel to a Z-axis. The intermediate drive gear 121 includes a small gear 121a and a disk 121b, the small gear 121a being in mesh with the large gear 120b and the disk 121b having a conical surface 121c. 
The loading motor 122 has a friction wheel 123 attached to a shaft thereof, the friction wheel 123 being in the shape of a truncated cone. The shaft of the loading motor 122 extends parallel to the main chassis 2 so that the conical surface 121c of the friction wheel 123 is in pressure contact with the conical surface 121 of the disk 121b. Thus, the rotation of the loading motor 122 is transmitted to the gear 121 through friction engagement of the friction wheel 123 with the disk 121.
The loading motor 122 is mounted on a generally L-shaped mounting member 124 by means of a screw 101. The mounting member 124 is firmly mounted on the main chassis 2 by means of screws 102.
FIG. 12 is a top view of the conventional disk-loading apparatus 1 when the tray is at the disk-loading position.
FIG. 13 is a perspective view that corresponds to FIG. 10.
FIG. 14 is a perspective view that corresponds to FIG. 12.
As shown in FIG. 13, a cam slider 50 is generally L-shaped, and is supported on the main chassis 2 so that the cam slider 50 can slide on a Y-axis. The cam slider 50 has a rack 50c formed in its side portion and bosses 50a and 50b that project upwardly from a top surface of the cam slider 50. The bosses 50a and 50b engage the guide grooves 3b and 3c formed in the underside of the tray 3.
As shown in FIG. 14, the cam slider 50 has a flat portion parallel to a Z-Y plane. Formed in this flat portion is the cam slider 50 having a cam groove 50d along which a later described projection 70a of a drive chassis 70 is guided to move. The cam groove 50d includes a lower end 101b, an upper end 110a, and an inclined portion 101c that connects the lower and upper ends 101b and 101a. 
The drive chassis 70 has a pair of bosses 70b and 70c (also see FIG. 15) that are in line with each other and project from opposite sides of the drive chassis 70. The drive chassis 70 is supported at the bosses 70b and 70c on the main chassis 2 and is rotatable about an axis 115 parallel to the Y-axis. The drive chassis 70 has a projection 70a that projects in a direction perpendicular to the axis 115.
The projection 70a loosely extends through the cam groove 50d formed in the cam slider 50. Therefore, when the cam slider 50 moves back and forth along the Y-axis, the drive chassis 70 rotates about the axis 115 in directions shown by arrows A and B. The drive chassis 70 carries a reproducing mechanism that includes an optical pick-up 76 and a turntable 77.
In the disk-loading operation, the tray 3 moves from the position (i.e., disk-discharging position) shown in FIG. 10 to the position (i.e., disk-loading position) shown in FIG. 12 where the optical pick-up 76 reproduces information from the disk.
When the loading motor 122 of FIG. 11 rotates in a direction shown by arrow C, the drive gear 120 rotates about an X-axis in a direction shown by arrow E. The rotation of the drive gear 120 in the E direction is transmitted through the small gear 120a and rack 3a to the tray 3. Thus, the tray 3 moves on the X-axis from the disk-discharging position of FIG. 10 toward the disk-loading position (i.e., toward the origin 0 of X-axis). In other words, the rotation of the loading motor 122 in the C direction causes the tray 3 to slide along the guides 2a-2e, thereby initiating a disk-loading operation.
FIG. 15 illustrates the conventional tray immediately before it reaches the disk-loading position.
When the tray 3 reaches a location very close to the disk-loading position, the bosses 50a and 50b move into engagement with the curved portions of the L-shaped guide grooves 3b and 3c to move the cam slider 50 on the Y-axis in a direction away from the origin O. The movement of the cam slider 50 on the Y-axis causes the rack 50c to move into meshing engagement with the small gear 20a of the drive gear 20. At this time, the rack 3a formed in the underside of the tray 3 is still in mesh with the small gear 20a of the drive gear 20. When the tray 3 has reached the disk-loading position shown in FIG. 12, the rack 3a disengages from the small gear 20a. 
The cam slider 50 continues to move on the Y-axis since the rack 50c remains in mesh with the drive gear 20 until the bosses 50a and 50b reach the ends of the guide grooves 3b and 3c of the tray 3, respectively, as shown in FIG. 12. When the bosses reach the ends of the guide grooves 3b and 3c, the cam slider 50 stops moving and the tray 3 completes the disk-loading operation.
The disk-loading operation will be described in more detail with reference to FIGS. 13 and 15.
The projection 70a remains in engagement with the lower end 101b of the cam groove 101 to maintain its inclined position with respect to the disk-carrying surface 3d until the bosses 50a and 50b start moving on the Y-axis in the direction away from the origin O. At this moment, the turn table 77 disposed on the drive chassis 70 has moved downward away from the disk-carrying surface 3d. 
Then, as soon as the tray 3 arrives at a location (FIG. 15) near the disk-loading position, the cam slider 50 starts moving on the Y-axis away from the origin O. Thus, the projection 70a of the drive chassis 70 starts engaging the inclined portion 101c of the cam groove 101 formed in the cam slider 50. Thus, the drive chassis 70 rotates about the Y-axis in the direction shown by arrow A. The drive gear 120 continues to rotate in the direction shown by arrow E, so that the rack 50c formed in the cam slider 50 moves into meshing engagement with the small gear 120a of the drive gear 120. Thus, at this moment, the drive gear 120 causes the tray 3 and cam slider 50 to move.
The drive gear 120 continues to rotate in a direction shown by arrow E, so that the tray 3 reaches and stops at the disk-loading position of FIG. 12 where the rack 3a moves out of meshing engagement with the small gear 20a of the drive gear 120. The cam slider 50 still continues to move on the Y-axis in the direction away from the origin O and stops at the position of FIG. 12 where the bosses 50a and 50b reach the ends of the guide grooves 3b and 3c. 
When the cam slider 50 moves on the Y-axis in the direction away from the origin O, the projection 70a of the drive chassis 70 is guided by the inclined portion 101c (FIG. 15) to move upwardly and then reach the upper end 110a. The upward movement of the projection 70a causes the drive chassis 70 to rotate through a predetermined angle about the axis 115 in the direction shown by arrow A, to the position of FIG. 15.
When the drive chassis 70 is rotating about the axis 115, the turntable 77 raises the disk, not shown, on the disk-carrying surface 3d of the tray 3 (FIG. 12) to hold the disk sandwiched between the turntable 77 and the clamper 60 on the main chassis 2. Then, the disk is driven in rotation so that the optical pickup 76 reproduces either continuously or intermittently the information recorded on the disk.
With the aforementioned conventional disk-loading apparatus 100, as soon as the rack 50c of the cam slider 50 moves into meshing engagement with the small gear 20a of the drive gear 20, the drive chassis 70 starts rotating to raise the recording and reproducing unit 90. Since the rack 50c has not moved yet into complete meshing engagement with the small gear 20a and the rotation of the drive gear 20 cannot be transmitted properly to the cam slider 50. This operation is disadvantageous in that a large load due to the upward movement of the recording and reproducing unit 90 is exerted on the rack 50c that is still incomplete meshing engagement with the small gear 20a. 
Thus, the rack 50c deforms so that the tray 3 is not pulled in smoothly into the apparatus and therefore the recording and reproducing unit 90 cannot move upward smoothly. Unpleasant noise also occurs when the mechanism switches from the pull-in of the tray into the upward movement of the recording and reproducing unit 90.
The present invention was made to solve the drawbacks of the aforementioned conventional disk-loading apparatus.
Another object of the invention is to provide a disk-loading apparatus that performs reliable disk-inserting and disk-discharging operations.
An object of the invention is to provide a disk-loading apparatus in which a disk-carrying tray can be inserted into and discharged out of the apparatus without making unpleasant noise.
A main chassis supports a tray that carries a disk thereon and slides between a disk-discharging position and a disk-loading position. A drive gear rotatably is mounted on the main chassis. A first rack is formed in the tray and is in meshing engagement with the drive gear when the tray is at the disk-discharging position, and becomes out of meshing engagement with the drive gear when the tray is at the disk-loading position. A cam slider has a second rack formed therein and a guide groove formed therein. The cam slider is movable relative to the main chassis in a first direction such that the second rack moves into engagement with the drive gear, and in a second direction opposite to the first direction such that the second rack moves out of meshing engagement with the drive gear. When the tray has moved to a location very close to the disk-loading position, the second rack starts moving into meshing engagement with the drive gear. The first rack becomes out of meshing engagement with the drive gear before the cam slider has moved into meshing engagement with the drive gear such that a pitch circle of the drive gear is tangent to a pitch line of the second rack. A disk-reproducing unit having an engagement portion that extends slidably into the guide groove. When the cam slider has moved into meshing engagement with the drive gear such that a pitch circle of the drive gear is tangent to a pitch line of the second rack, the engagement portion starts being guided along the guide groove so that the disk-reproducing unit starts rotating in a third direction about an axis to a disk-reproducing position. When the cam slider moves in the second direction, the disk-reproducing unit rotates in a fourth direction opposite to the third direction about the axis to a non-disk-reproducing position.
The engagement portion extends in a fifth direction substantially perpendicular to the axis and the axis extends in a sixth direction parallel to a plane in which the tray moves between the disk-discharging position and the disk-loading position.
The first and second directions are perpendicular to a seventh direction in which the tray moves between the disk-discharging position and the disk-loading position.
The cam slider is in cam engagement with the tray such that when the tray moves toward the disk-loading position, the second rack is brought into meshing engagement with the drive gear.
The guide groove guides the engagement portion of the disk-reproducing unit such that the disk-reproducing unit starts rotating to the disk-reproducing position, only after the pitch circle of the drive gear is tangent to the pitch line of the second rack.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.